摘要： In this paper, octagonal-photonic crystal fiber (O-PCF) has been proposed for studying liquid types for sensing applications. The propagation properties for the proposed O-PCF were studied numerically by utilizing full-vector finite element method (FV-FEM ) using COM SOL M ultiphysics version 5.1. The confinement loss, the relative sensitivity, and the nonlinearity coefficient can be controlled by changing the factors related with the geometry such as the cladding in a range of wavelength, air hole diameter, and the core pitch. The proposed O-PCF is realized with three rings from the air hole in the cladding and two circular rings in the core region. Numerical simulation of the proposed structure is achieving the highest sensitivity by increasing the diameter of the air hole the cladding, while the pitch remains constant. At the same time, the confinement losses have distinguishable decrease with an increase in diameter as well as an increase in the number of rings within the cladding layer. In addition, the effective area and the nonlinear coefficient each of them is affected with every hole of the diameter and with the type of the chemical material used. The proposed model shows that the fiber is of a high efficiency not only in the sensing application, but also being distinguishable with the nonlinear optical application.